Jon W and I did this a while back with our '99s, but we removed the upper intake manifold to facilitate the process. You'd be amazed by how much gunk we cleaned off.
Unfotunately, it's a little more involved to remove the upper half of the intake manifold, but we still managed to do mine in a little over an hour from start to finish. We also used liberal amounts of intake cleaner (about two cans each), and a wire brush to get some of the more stubborn gunk off.